Fluid pressure responsive device



May 23, 1933 J. R. coFFlN ET AL 1,910,322

FLUID PRESSURE RESPONSIVE DEVICE Filed Aug. 6, 1929 I/venoms: John 1%.00 fin, d ZexaW/deznl @9968, Z x' y M`M M? @es Cil Patented May 23, 1933 .UNITED STATES PATENroFi-icg JOHN R. COFFIN, OF WEST MEDFORD,

CORPORATION OF MASSACHUSETTS f AND ALEXANDER 5'.' TIGGES, 0F BOSTONQ-MASSA- CHUSETTS, ASSIGNORS TO BAROSTAT COMPANY,

"0F BOSTON, MASSACHUSETTS, A

FLUID PRESSURE RESPONSIVE l:DEVICE Application filed August 6, 1929. Serial No. 383,966.

This invention Irelates to improvements iii fluid-pressure responsive devices, 'of the class which employ resilient, y snapping diaphragme designed to move abruptly in response to pressure changes. Such devices commonly employ an adjustable diaphragmloading spring, acting more or less directly on the diaphragm to vary the pressure at which the latter will respond. Siicli methods of adjustment not only tend to impair the characteristics of the diaphragm, but the range of adjustment within which satisfactory operation is possible is comparatively small. 'lnV the vdevice* described herein, there is disclosed adjusting means which permits of adjustment over wide ranges, with no impairment of the operating characteristics of the diaphragm. Moreover, the characteristics of the diaphragm-loading means'ot the present invention are such that the movement of the diaphragm is multiplied before it reaches the device which it actuates. This is highly desirable in case the device to be actuated is an electric switch. The invention also relates to novel and improved means or variably limiting the range of movement of the snapping diaphragm.

The invention will be best understood by reference to the following description, when taken in connection with the accompanying drawing of one specific embodiment thereof, while its scope will be more particularly pointed out in the appended claims.

In the drawing:

Fig. 1 is a sectional view of a fluid-pressure responsive device embodying the invention, taken in the plane containing the main axis of the device; v, v y

Fig. 2 isa side elevation of the upper portion of the device; andv f i Fig. 3 is a sectional view on line 3-3 of Fig. 2.

Referring to the drawing, and to the embodiment kof the invention which is illustrated therein, there is 'shown a fluid-pressure responsive device presenting two pressure-fluid chambers l() and 11, having a common wall comprising a resilient, buckling or snapping diaphragm 12, adapted to buckle in opposite directions, but prevented by its own'resihencyfrom` remaining in a medial position. The chambers are formed by and within a casing, herein conveniently y comprising two bodies or shells 13 and 14, suitably secured to each other as by bolts 15, while packing rings 16 above land below the margin of thief-diaphragm prevent lealtage, these rings being held under compression by the bolts. A

' The chamber 10 is sealed, 'and has another wall comprising a non-resilientdiaph'ra'gm 17, herein of much smaller areathan that of the diaphragm 12, as a result of which a certain movement of the latter results a much greater movement of the former, The chamber 10 is provided with a lilling plug 18, removal of which enables the chamber to be filled with an appropriate fluid caus- Y ing movement of one diaphragm to be transl' mitted to the other. f In the present eXample, this Vluid is'aliquid such as oil. The liquid, beingfincompressi'ble, transmits the motion without loss due to compression,

-which would be occasionedby the use of a compressible gas.y The diaphragm 12 is actuated by pressure-fluid admitted.` to the chamber. 11 through a passage 19 leadingto the exterior. Y A

.Referring again to the diaphragm 17, the latter receivesthe thrust'of a diaphragmloading spring 20, herein through a movable abutment21` interposed between the spring and the diaphragm. As shown, .this abut-v ment and the spring are 'contained in acylindricalshell 22, suitably secured to thel shell4 13, as by providing the former with a flange 23 to receivel cap-screws 2,4 which secureV the two Vshells together and clampv the margin of the diaphragm 17y therebetween. An annular shoulder 25, presented by the shell 22,liinits movement of the abutment 2l in onedirection, while stops, herein screws 26 threaded through the. circumferential wall of the shell 22, limit movement of the'abutment in the opposite direction, thereby protecting the diaphragm against injury dueto too great movement.

By imposing the load of the spring l through the movable abutment 21 upon the diaphragm 17, the load is communicated by the confined liquid to and is distributed upon the snapping diaphragm 12, without impairing the characteristics of the latter. On the other hand, by simply making the diaphragm 17 of smaller area than the diaphragm 12, the motion of the latteris multiplied, without the use of external mechani`` .cal agencies. The adjustableloading vof the A.diaphragm is conveniently` accomplished in the present example by interposing the spring between the movable abutment 21 and an abutment 27, which, though xed in the operation of the device, is adjustable as by the use of a screw-thread 28 between the abutment 27 and the shell 22. Byl turning the abutment 27 in the proper direction, the spring pressure may be varied at will, within maximum and minimum limits predetermined by stops, herein screws 29 and 30, threaded through the circumferential wall of the shell 22. By the use of these stops, the maximum and minimum loads imposed by the spring upon the snapping diaphragms are predetermined. It should of course be understood that this adjustable loading is applied uniformly over the surface of the diaphragm 12. The total force which must be applied by means of the spring is comparatively small, because the area of the diaphragm 17 to which the force is applied is much smaller than the whole area of the diaphragm 12.

As an additionalmeans of control of the snapping diaphragm 12, there is provided within the chamber 1() an abutment in the form of a ring 31, conveniently adjustable by screws 32 threaded into the shell 13, and rendered accessible for adjustment by first removing sealing screws 33. By adjusting the-position ofl the ring relatively to the diaphragm, the spread and the pressure level of the Huid pressure controlled by the snapping diaphragm may be varied simultaneousl Aother method of adjustment is obtainable through the use of an adjustable abutment 34, which limits downward movement of the diaphragm 12. This abutment is conveniently adjustable from-,the exterior of the device, but without'the use .of packing, by providing the chamber 11 with la wally comprising a non-resilient diaphragm 35, which is clamped between the shell 14 and a cover-plate36, by the same bolts 15 lwhich secure the shells 13and 14 together. Gaskets or packing rings 37 between the upper and lower faces of the margin of the diaphragm 35 and theshell 14 andocoverplate 36 prevent leakage at this point.

' The abutment 34, as shown, is a head which is suitably formed on or secured to one end of a stem 38, which is guided by an appropriate guide 39, herein presented by a spider 40. Suitably formed on or setions extend through grooves cured to the lower end of the stem 38 is a head 41, which engages the diaphragm 35. Thus, it is apparent that by the use of a stop below the diaphragm 35, downward travel of the snapping diaphragm 12 may be limited. This is conveniently accomplished in the present case by the use of an adjusting'screw 42, threaded into the cover-plate 36.' As shown, this screw has its inner end swivelledfto a head 43, secured as by soldering to the under side of the diaphragm 35, and at the exterior of the devicepthere is-a knurled head 44, which may be grasped .toA turn the screw. Still another means of control of the diaphragm is through the use of. a spring y45, interposed between the head 34 andthe spider 40. This gives a type of control over .the operating pressure which is sometimes desirable.. y A

While the .device may be used to actuate various devices, there is shown in the drawing a'switch mechanism .intended to open and closea circuit such as, that of a motor for driving a compressor in a refrigeration system with which the chamber 11 communicates.` This -mechanism will now be described, reference being had at first to Fig. 1. Resting upon the movable spring abutment 21 is a plunger 46, vwhich extends through and is guided by the adjustable spring abutment 27. To this rod there is secured a cross-member or cross-head 47, upon .which rests a shoulder 48 presented by an insulatingmember 49, which carries a pair of switch contacts 50, electrically connected to eachother, as by a ring 51. These contacts are adapted to make and break connection with contacts `52 carried by a second insulating member 53, separation of one ,pair` of contacts from the other being normally. maintained by a spring 54, interposed between the insulating members 49 and 53, said spring constantly yexerting a downward thrust upon the member 49, and thus through the cross-head 47 maintaining engagement of the rod 46 with the abutment 21. This, of course, presupposes that the insulating member 53 is suitably held against upward displacement. This is conveniently accomplished by securing the member 53 by suitable means such as screws 55 to upwardly-extending projections 56 presented by the shell 22.v These projec- 57 presented by the insulating member 49, and prevent rotationof the latter. A- sleeve .58.extends axially through the insulating members 49 and 53, and is suitably secured, as by a setvscrew 59 .to the abutment 27.L The sleeve is provided with. vertical slots60, in which the cross-head 47 plays up and down. The upper end of the sleeve is suitably formed, asby the provision of a polygonal head 6l for rotation-ofthe adjustable spring abut- .unimaas ment 27. The contacts 52 are appropriateiy secured to the insulating member 53, as by binding posts v62, intended to be connected to the controllers of the motor which drives the refrigerant compressor.

Having thus described one embodiment of thejinvention, but withoutilimiting ourselves thereto, what we claim and desire by Letters Patent to secure is:

l. In a pressure-fluid responsive device, the combination of two chambers having a common wall comprising a resilient, snapping diaphragm, a constantly open pasmge to conduct fluid into and out of one of said chambers for the continuous admission of pressure fluid to actuate said diaphragm, the other chamber being sealed and having a wall comprising a second diaphragm having no connection with said snapping diaphragm, a. liquid within said other chamber between said diaphragm and presenting the sole means to transmit motion from one diaphragm to the other, and means actuated by said second diaphragm.

2. In a pressure-Huid responsive device, the combination of two chambers having a common wall comprising a diaphragm, one of said chambers having .a lluid sealed therein and having another wall comprising a second diaphragm having no connection with the first-mentioned diaphragm, there being a constantly open passage leading from the other chamber to the exterior forthe continuous admission of pressure fluid to operate the first-mentioned diaphragm, and means actuated by said second diaphragm.

3. In a pressure-Huid responsive device, the combination of two chambers having a common wall comprising a diaphragm, one of said chambers being sealed and having another wall comprising a second diaphragm of smaller area than the iirst, a huid .between said diaphra-gms constituting the sole operative connection to transmit movement from `one to the other, there being a passage leading from the other chamber to the exterior, loading means for said second diaphragm, and means independent of said loading means and actuated by said second diaphragm.

4. In a pressure-fluid responsive device, the combination of two chambers having a common wall comprising a diaphragm, one of said chambers being sealed and having another wall comprising a second diaphragm, a fluid between said diaphragme constituting the sole operative connection to transmit movement from one to the other, there being a constantly open passage leading from the other chamber to the exterior for the continuous admission of pressure fluid to operate the first-mentioned diaphragm, loading means exerting a pressure on said second diaphragm in the direction of the first diaphragm, and means independent of said loading means and actuated by said .second diaphragm in the opposite direction.

5. In a pressure-huid responsive device, the combination of two chambers having a vcommon wall comprising a diaphragm, one

ofasaid chambers being sealed and having another wall comprising a second diaphragm of smaller area than the first, a iiuid between said diaphragms constituting the sole operative conection to transmit movement from one to the other, there being a passage leading :tromthe other chamber to the exterior, loading means exerting a pressure on said second diaphragm in the direction of the first diaphragm, and means second diaphragm. v

6. In a pressure-duid responsive device, the combination of twov chambers having a common wall comprising a diaphragm, one of said chambers being sealed and having another wall comprising a second diaphragm of smaller area than the first, a lliuid between said diaphragms constituting the sole operative connection to transmit movement from one to the other, there being a constantly open passage leading from the other chamber to the exterior for the continuous admission of pressure fluid to operate the firstmentioned diaphragm, a loading spring exerting a pressure on said second diaphragm in the direction of the first diaphragm, means for adjusting said spring to varysaid pressure, and means independent of said spring and actuated' by said second dia- Phrase 7. In Aa pressure-fluid responsive device, the combination of two chambers having a common wall comprising a diaphragm, one of said chambers being sealed and having another wall comprising a. second diaphra-gm, loading means for'said second diaphragm, a liquid within said sealed chamber to transmit movement from one diaphragm to the other, there being a constantly open passage leading from the other chamber to the exterior for the continuous admission of pressure fluid to operate the first-mentioned diaphragm, and means independent of' said loading means andactuated by said second diaphragm. I

8. Ina pressure-fluid responsive device, the combination of two chambers having a common vwall comprising a diaphragm, one

of said ,chambers being sealed and havingv another wall comprising a second diaphragm of smaller area than the first, loading means for said second diaphragm, a liquid within said sealed chamber to transmit movement from one diaphragm to the other, there being y a constantly open passage leading from the other chamber tothe exterior for the admission of pressure fluid to operate the firstmentioned diaphragm and means'independent of said loading means and actuated by saidv seconddiaphragm.

actuated by said lll) , common. wall comprisingk a` diaph -admission of first-mentioned diaphragm, `loadmg means A 9. In a pressure-fluid' responsive device, the combination of two chambershavmga ragm,.one of sald chambers bemg'llsealed andhaving another wall comprising# a Vsecond-d1a -phragm, a liquid within'said .sealed chamber to transmit movement from-I one `diaphragm to the other, there being a constantl; open passage leading. from'lthe other c amber to the exterior for the continuous pressure liuid to1 Voperate the exerting a pressure Aonzsaid, secondi diaphragm in the di-rection of the irst diaphragm, and-means independent of said; loading means and actuated byv said second v diaphragm in the opposite direction.

l0. In a pressure-huidaresponsive.V device, the combination of two chambers having a common wall comprising a diaphragm, one of said chambers being sealed and having a wall comprising a'second diaphragm, a fluid between said diaphragms constituting the sole operative'connectionto transmit movement from one to the other, there being a constantly open passage leading. from-'the other chamber to the exterior for the continuous admission of pressure fluid to operatek the first-mentioned diaphragm, means to limit movement of the first-mentioned diaphragm, and Ameans independent of. the rst-men Itioned means and 'actuated byvsaid `second diaphragm. l .Y -f 1 l1. In a pressurediuid ,responsivedevicq the combination of two chambers having a common wall comprising a diaphragm,`vone of said chambers being sealed andhaving a wall comprising `a second diaphragm. having no connection kwith the. hist-mentioned diaphragm, there being a passageleading from the other chamber to thezexterior, anlabutment to limit movement of the first-mentioned diaphragm, means accessible from the exterior of the device`to=adjustfsaid abutment, and means-actuated by said second diaphragm. Y"

12. 4In a pressure-Huid responsive device, the combinationk of twochambers having-a common wallcomprising a diaphragm, one of said chambers being sealed and having a wall comprisingV a second diaphragm, there being a passage leading fromtheotherchaml 1 v ber to the exterior, abutments to limit movement of theyfirst-mentioned;diaphragm'fin means accessible 'from opposite directions, the exterior ofthe deviceto adjust lone of -said abutments, EIncansva'ccessible from the exterior of thev device to `adjust the other abutment, and means actuatedby said second diaphragm. i n 13. In a pressure-Huid responsive device, the combination of two chambershavlng a of said chambers being sealed andhaving a wall comprising a ysecondldiaphragimjvthe .n

'terior, vfirst vand'third diaphragms, and means disposed externally'of said second vchamber ad- 'Justably toflimit movementof the first diasecond chamber having a walll comprising a third diaphragm, there being a passage leading from saidsecondchamber to the exterior,^anabutment -interposed between the first and'fthird.;diaphragms,'.and means disposed externally of' said 4second chamber to imitmovement 'of vthe'iirst diaphragm toward theithirdv diaphragm."

14. In a pressure-fluid responsive device,

`thecombination `of two chambers having a `common wall comprising adiaphragm, one of saidl chambers being sealed and having a wallv comprising 'asecondt diaphragm, the second chamberhaving a wall comprising a thirdV diaphragm, there being anpassage leading'lfrom said second chamber to the exan abutment interposed 'between the the combination of two chambers having a vcommon `wall comprising a diaphragm, one 'of said chambersbelng sealed and having a wall comprisinga second diaphragm, a loading spring exerting second diaphragm vinil the direction of the irst diaphragm, aV movable fabutment interposed between said spring'land the secondl diaphragm, means to -limit movement of said abutment under the ini'iuence of the second diaphragm, there being a passage leading from fthe second chamheryto the exterior, andfmeans actuated by the second diaphragm. ff

In testimony whereof, we have signedv our names to this specification.v

JOI-IN R. COFFIN. v

j :TIGGES .common-wall comprising a1diaphragm,one j pressure-fluid responsive device,-

a pressure en the 

